New UH study shows how rising sea levels will erode most Hawaii beaches

I know, there’s a public relations rule that bad news typically drops on Fridays, but scientists rarely adhere to such traditions. Which is why the University of Hawaii sent me yet another alarming news release today on how global sea level rise will cause even more damage to our shorelines than previously estimated.

“For the study, published this week in Natural Hazards, the research team developed a simple model to assess future erosion hazards under higher sea levels – taking into account historical changes of Hawai‘i shorelines and the projected acceleration of sea level rise reported from the Intergovernmental Panel on Climate Change (IPCC),” states the Mar. 23 UH news release. “The results indicate that coastal erosion of Hawai‘i’s beaches may double by mid-century.”

We’re not talking big changes centuries from now–the new UH research indicates that those living and working near the shore will see considerable erosion in the next few decades.

“This means that the average amount of shoreline recession roughly doubles by 2050 with increased SLR, compared to historical extrapolation alone,” said Tiffany Anderson, the study’s lead author and a post-doctoral researcher at the UHM School of Ocean and Earth Science and Technology, in the news release. “By 2100, it is nearly 2.5 times the historical extrapolation. Further, our results indicate that approximately 92% and 96% of the shorelines will be retreating by 2050 and 2100, respectively, except at Kailua, Oʻahu, which is projected to begin retreating by mid-century.”

There is some slim hope: the new study shows exactly which beaches will see the worst erosion, allowing the “thousands” of exposed residents to see how much their neighborhoods will change.

“This study demonstrates a methodology that can be used by many shoreline communities to assess their exposure to coastal erosion resulting from the climate crisis,” said Chip Fletcher, Associate Dean at the UHM School of Ocean and Earth Science and Technology and co-author of the paper, in the news release.

“Mapping historical shoreline change provides useful data for assessing exposure to future erosion hazards, even if the rate of sea level rise changes in the future,” stated the news release. “The predicted increase in erosion will threaten thousands of homes, many miles of roadway and other assets in Hawai‘i. Globally the asset exposure to erosion is enormous.”

We’ve been writing about Hawaii beach erosion for a while–in fact, click here for a story from 2006 on Fletcher and UH projections at that time.